Evrim Yazgin
Cosmos science journalist
Seismologists in Australia have detected signals which travelled through the Earth’s core from strong winter storms in the North Atlantic Ocean. They say their data could help future space exploration missions.
Hurricanes (called cyclones in the southern hemisphere) in the North Atlantic are storms powerful enough that they can actually cause mini earthquake-like signals. These are called “microseisms” and are usually generated by the interaction of strong surface waves with the ocean floor.
In the new study, published in the journal Seismological Research Letters, researchers from the Australian National University (ANU) detected signals from the other side of the world.
Microseisms from storms in Newfoundland, Canada and Greenland were measured at 50km-by-50km spiral-arm arrays in Western Australia and southern Queensland.
The microseisms caused PKP waves – a type of seismic wave which travels through the Earth’s mantle, then the outer core and then the mantle again.
“We combined data from multiple days to identify the regions where the signals were strongest, providing insights into the source and transmission of the seismic waves,” says co-author and ANU PhD student Abhay Pandey. “The signals are tiny in amplitude and often below the observational threshold of a single sensor, requiring specific instrument designs to record them.
“The signals are difficult to record, but the observational infrastructure in remote and ‘quiet’ parts of the Australian continent and its unique geographic position makes it ideal for observing them.”
Co-author Hrvoje Tkalčić, also from ANU, says microseismic phenomena can be an alternative data source to study the Earth’s structure beneath Australia.
“The signals are complex and varying based on the source and receiver path, and require efficient methods and modern observational infrastructure, including our national ocean bottom seismometer pool to detect and record them.”
The researchers say their detection method could be used to identify planets which could be targets for future space exploration missions.
“This method, particularly in the context of exploring other planets and icy moons, can be used to identify planets with a core, including those that don’t have plate tectonics or volcanoes and ones that don’t experience quakes, providing valuable data for future exploration,” says Pandey.
“If we can land a seismometer array on the surface of a small planet without quakes, the method might be handy for scanning their interiors by using the atmospheric and hidden ocean signals that resemble the ones from our study,” Tkalčić explains.